The present invention relates to shutter mechanisms and in particular to a shutter mechanism designed to operate in a harsh environment. Such shutters may be found, for example, on hot box detector scanners such as those disclosed in U.S. Pat. Nos. 3,108,733 and 3,545,005. Such scanners utilize infra-red sensors to scan and obtain heat readings of the bearings of moving railroad trains to look for overheated bearings that are in danger of failing. The scanners are usually mounted alongside railroad tracks and very often are in remote areas. As a train approaches the scanner, an appropriate signal is triggered to open the shutter thereby exposing the infra-red optics to the passing bearings. The shutter is necessary to protect the relatively sensitive optics from the environment, animals and vandals. Thus, the shutter should remain locked in the closed position until actuated to open whereafter the shutter should lock in the open position until train passage is complete and the shutter is activated to close. In view of the harsh conditions under which the shutter may be called upon to operate and because of the high degree of reliability demanded, the movement of the shutter should be relatively simple and the shutter actuation device should likewise be relatively simple and capable of being remotely actuated.
In view of the above, it is the principal object of the present invention to provide an improved shutter mechanism which is self locking in both its closed and open positions.
Another object is to provide such a shutter mechanism which is adapted to shift from one of its locked positions to the other of its locked positions upon actuation of a solenoid.
A still further object is to provide such a shutter mechanism wherein the shutter rotates between open and closed positions through an arc of 45.degree. in response to solenoid actuation.
A still further object is to provide such a mechanism which may be utilized with conventional optic systems with little or no modification.